SummarySolidago nemoralis Aiton (Compositae: Astereae: Solidagininae) is illustrated and described, and its extensive synonymy provided (covering both proposed subspecies), together with full type citations and location of known types and relevant commentary. The position of the somewhat daunting genus Solidago L., and its position within the tribe Astereae is discussed. Solidago nemoralis is placed with a small cluster of species (with just S. decemflora and S. nana) in its own subgenus and subsection, Solidago subgen. Nemorales (Mack.) Semple & J. B. Beck subsect. Nemorales (Mack.) G. L. Nesom. Cultivation, propagation, pests and diseases and availability of S. nemoralis are commented on. Differences between S. nemoralis, a predominantly diploid species with a few tetraploid populations, and S. decemflora, a tetraploid species throughout its range, are noted, and the two maintained as distinct species.